In order to ensure that 2Checkout calls back your Kartris site to notify it that a payment for a particular order was made so that confirmation mails can be sent and the order can be tagged as 'paid', you need to set up a few things within your 2Checkout account.

1. Login to 2Checkout and go to Account > Site Management.
2. The 'Approved URL' will be http://www.mysite.xyz/Callback-2checkout.aspx and the 'Direct Return' should be set to 'Immediately return to my web site'.

2Checkout should now be set up and working. We would advise that you always test a site in live mode when you first open it (status = 'ON') even if all the test modes checked out ok. This confirms that everything is working with Kartris and that your account with 2Checkout is live and working. The best way is to create a low value product of a dollar which you can purchase.